JP2020128520A - Fluororesin particle and method for producing the same - Google Patents

Abstract

To provide a fluororesin particle having excellent flowing and filling properties and a method for producing a fluororesin particle.SOLUTION: A resin particle has a residue unit represented by general formula (1) and has a volume average particle size of 5 μm or more and 2000 μm or less. In formula (1), Rf, Rf, Rf, and Rfindependently represent one selected from the group consisting of a fluorine atom, a C1-7 linear perfluoroalkyl group, a C3-7 branched perfluoroalkyl group or a C3-7 cyclic perfluoroalkyl group. The perfluoroalkyl group may have ether oxygen. Rf, Rf, Rf, and Rfmay be mutually coupled to form a C4-8 ring.SELECTED DRAWING: None

Description

The present invention relates to a fluororesin particle having excellent fluidity and filling property and a method for producing the same.

Fluorine-based resins have excellent electrical properties, chemical resistance, waterproofness, and liquid/oil repellency, so they are used as protective films for electronic components such as semiconductors, water-repellent films for inkjet printer heads, and water- and oil-proof coatings for filters. ing.

Among them, a fluororesin containing an oxolane ring has a bulky ring structure and thus is amorphous and has high transparency and high heat resistance. Further, since it is composed only of carbon, fluorine and oxygen, it has high electrical properties, chemical resistance, waterproofness and liquid repellency and oil repellency. Furthermore, since it is amorphous, melt molding is possible.

Patent Document 1 describes a polymer of perfluoro(2-methylene-4-methyl-1,3-dioxolane (PFMMD)) as a fluororesin containing an oxolane ring and a method for producing the same. Is a description of an example in which a polymer of perfluoro(2-methylene-4-methyl-1,3-dioxolane) was polymerized in the presence of nitrogen fluoride (N ₂ F ₂ ) in a glass sealed tube. No solvent is used and no specific form of the obtained polymer is described in Non-Patent Document 1. PFMMD as a fluororesin containing an oxolane ring is bulk-polymerized or solution-polymerized to obtain the polymer. In the present specification, unless otherwise specified, a resin and a polymer are described as synonymous.

US Patent No. 3308107

Macromolecules 2005, 38, 4237

Non-Patent Document 1 describes that in the case of bulk polymerization, if the purification is not performed after the polymerization, the optical characteristics and heat resistance of the resin are deteriorated, but the purification reduces such deterioration. In solution polymerization, chloroform is added and precipitated after polymerizing using either of two types of fluorine-based solvents. There is no description of the specific form of the resin obtained by purification of bulk polymerization and the resin obtained by adding chloroform to cause precipitation.

As a result of a study by the present inventors, the resin obtained by the method described in Patent Document 1 and Non-Patent Document 1 had an amorphous non-particulate morphology. Therefore, there is a problem in the fluidity of the resin. For example, when melt-molding a resin, it has been found that there is a problem in handling such that it becomes difficult to continuously supply the resin into the molding machine. Further, since the resins described in Patent Document 1 and Non-Patent Document 1 have the above-described forms, when the resin is filled in a molding machine, for example, a desired weight of the resin cannot be filled in a predetermined volume, that is, the filling is performed. It was also found that there is a problem of low sex. In this respect, since a container having a large volume with respect to the weight of the resin is required, there is a problem that the economical efficiency in transporting the article is lowered.

Therefore, an object of the present invention is to provide a resin particle containing a residue unit represented by the general formula (1), which is excellent in fluidity and filling property, and a method for producing the same, in order to solve the above problems. ..

Further, as a result of further study by the present inventors, the resin produced by the method described in Patent Document 1 and the non-patent document has an amorphous non-particulate morphology, so that It is difficult to remove the entrapped solvent. When the solvent remains in the resin, there is a problem that the amount of weight loss during heating is large, foaming occurs during molding, and the working environment during molding is deteriorated.

Therefore, an object of the present invention is to provide a resin particle containing a residue unit represented by the general formula (1), which has not only excellent fluidity and filling property but also a small heating weight loss amount, and a method for producing the same. To do.

In addition, in producing a fluororesin, it is generally possible to obtain resin particles by means of emulsion polymerization, suspension polymerization, or the like. However, in these methods, an emulsifier or a dispersant is used as a polymerization aid. However, the emulsifier or dispersant used remains inside the resin particles to become a foreign substance, and further causes coloring when the resin is heated, possibly impairing transparency and heat resistance. There has been a possibility that the strict cleanness required for recent semiconductor peripheral members may not be satisfied.

Therefore, the present invention provides a method for producing resin particles containing a residue unit represented by the general formula (1) having excellent fluidity and filling properties without using an emulsifier and/or a dispersant, and an emulsifier and/or It is also an object to provide a resin particle containing a residue unit represented by the general formula (1), which does not contain a dispersant.

Further, the present invention is a resin particle containing a residue unit represented by the general formula (1), which has not only excellent fluidity and filling property but also small thermal weight loss and does not contain an emulsifier and/or a dispersant. And its manufacturing method.

The present inventors have found that novel resin particles containing a residue unit represented by the following general formula (1) and having a volume average particle size of 5 μm or more and 2000 μm or less are excellent in fluidity and filling property. This has led to the completion of the present invention.

In the formula (1), Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched perfluoroalkyl group having 3 to 7 carbon atoms. 1 type of the group which consists of a fluoroalkyl group or a C3-C7 cyclic perfluoroalkyl group is shown. The perfluoroalkyl group may have an etheric oxygen atom. Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may be a ring containing an etheric oxygen atom.

Furthermore, the present inventors were able to obtain resin particles without using an emulsifier or dispersant by using a precipitation polymerization method using a specific organic solvent, and obtained without using an emulsifier and a dispersant. The resin particles do not contain an emulsifier and a dispersant, are resin particles that retain the original transparency and heat resistance of the resin, and further, the solvent does not remain inside the resin particles, and the heating weight reduction amount is small. It has been found that particles can be obtained, leading to a preferred embodiment of the present invention.

The present invention is as follows.
[1]
A resin particle comprising a residue unit represented by the following general formula (1) and having a volume average particle diameter of 5 μm or more and 2000 μm or less.
(In the formula (1), Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched perfluoroalkyl group having 3 to 7 carbon atoms. 1 represents one of a group consisting of a perfluoroalkyl group or a cyclic perfluoroalkyl group having a carbon number of 3 to 7. The perfluoroalkyl group may have an etheric oxygen atom, and Rf ₁ and Rf. ₂ , Rf ₃ and Rf ₄ may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may be a ring containing an etheric oxygen atom.)
[2]
The resin particles according to [1], wherein the volume average particle diameter is 5 μm or more and 500 μm or less.
[3]
The resin particle according to [1] or [2], which has an angle of repose of 5° or more and 60° or less.
[4]
The resin particles according to any one of [1] to [3], which are precipitation polymerized products.
[5]
The resin particles according to any one of [1] to [4], which have a bulk density of 0.2 g/mL or more and 1.5 g/mL or less.
[6]
The resin particles according to any one of [1] to [5], which have a weight loss of 1% by weight or less when heated at 250°C.
[7]
The resin particles according to any one of [1] to [6], wherein the resin particles do not contain an emulsifier and/or a dispersant.
[8]
[1] to [wherein the residue unit represented by the general formula (1) is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by the general formula (2). 7] The particle according to any one of items.
[9]
A step of subjecting a mixture of a radical polymerization initiator, a monomer represented by the following general formula (3) and an organic solvent to polymerization conditions to obtain a resin containing a residue unit represented by the general formula (4). Have,
The organic solvent, at least the monomer is dissolved, and at least a part of the resin produced by the polymerization is not dissolved, is a solvent that causes precipitation of the resin,
The method for producing resin particles according to any one of [1] to [7], wherein the resin produced by the polymerization is precipitated as particles in an organic solvent.
(In the formula (3), Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched chain having 3 to 7 carbon atoms. Represents a perfluoroalkyl group or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms, wherein the perfluoroalkyl group may have an etheric oxygen atom, and Rf ₅ , (Rf ₆ , Rf ₆ and Rf ₇ may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may be a ring containing an etheric oxygen atom.)
(Definition of _{Rf 5, Rf 6, Rf 6} , and Rf ₇ in the formula (4) are the same as defined formula _{(3) Rf 5, Rf 6} , Rf 6, and Rf ₇ definitions in.)
[10]
The organic solvent is an organic solvent that dissolves the monomer represented by the general formula (3) and does not dissolve the resin containing the residue unit represented by the general formula (4), [9] Manufacturing method.
[11]
The organic solvent contains resin particles having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ including a residue unit represented by the general formula (4), which is 10 times (w/w) the resin particles. The production method according to [10], which is an organic solvent in which resin particles can be visually confirmed to remain in the organic solvent after being immersed in the organic solvent at 50° C. for 5 hours or more.
[12]
The organic solvent contains resin particles having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ including a residue unit represented by the general formula (4), which is 10 times (w/w) the resin particles. After immersing in the organic solvent at 50° C. for 5 hours or more, the solution is cooled to 25° C., and the resin sample remaining as a solid state is recovered. The manufacturing method according to [10] or [11].
[13]
The production method according to any one of [9] to [12], which uses an organic solvent containing a fluorine atom and a hydrogen atom in the molecule.
[14]
The method according to claim 13, wherein an organic solvent having a hydrogen atom content in the solvent molecule of 1% by weight or more is used.
[15]
The monomer represented by the general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by the general formula (5), and is represented by the general formula (4). [9] to [13], wherein the residue unit is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by the general formula (6). Manufacturing method.

According to the present invention, it is possible to provide fluororesin particles having excellent fluidity and filling properties, and a method for producing fluororesin particles.

Further, according to the present invention, not only is the resin particles not only excellent in fluidity and filling property but also containing no emulsifier and dispersant and a method for producing the same, and the fluidity and filling property are excellent, and the heating weight loss is small. A resin particle and a method for manufacturing the same can be provided.

FIG. 3 is a diagram showing a particle size distribution of resin particles produced in Example 1. FIG. 5 is a diagram showing a particle size distribution of resin particles produced in Example 4.

The present invention will be described in detail below.

The present invention is a resin particle containing a residue unit represented by the general formula (1). Since the fluororesin particles of the present invention have the bulky ring structure contained in the general formula (1), they are amorphous and have high transparency and high heat resistance. Further, since it is composed only of carbon, fluorine and oxygen, it has high electrical properties, chemical resistance, waterproofness and liquid repellency and oil repellency.

The Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ groups in the residue unit represented by the general formula (1) in the present invention are each independently a fluorine atom or a linear perfluoroalkyl group having 1 to 7 carbon atoms. Group, a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an etheric oxygen atom. Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may be a ring containing an etheric oxygen atom.

Examples of the linear perfluoroalkyl group having 1 to 7 carbon atoms include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, an undecafluoropentyl group, a tridecafluorohexyl group, Examples thereof include a pentadecafluoroheptyl group, and examples of the branched perfluoroalkyl group having 3 to 7 carbon atoms include a heptafluoroisopropyl group, a nonafluoroisobutyl group, a nonafluorosec-butyl group, a nonafluorotert-butyl group, and the like. Examples of the cyclic perfluoroalkyl group having 3 to 7 carbon atoms include a heptafluorocyclopropyl group, a nonafluorocyclobutyl group, a tridecafluorocyclohexyl group, and the like. Examples of the linear perfluoroalkyl group which may have an etheric oxygen atom having 1 to 7 carbon atoms include, for example, —CF ₂ OCF ₃ group, —(CF ₂ ) ₂ OCF ₃ group, and —(CF ₂ ) ₂ OCF ₂ CF ₃ groups and cyclic perfluoroalkyl groups having 3 to 7 carbon atoms and optionally having an etheric oxygen atom include, for example, 2-(2,3,3,4,4,5,5). 5,6,6-decafluoro)-pyrinyl group, 4-(2,3,3,4,4,5,5,6,6-decafluoro)-pyrinyl group, 2-(2,3,3,3) 4,4,5,5-heptafluoro)-furanyl group and the like.

Because of excellent heat resistance, at least one of Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ is a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched perfluoroalkyl group having 3 to 7 carbon atoms. It is preferably one member of the group consisting of a perfluoroalkyl group and a C3-7 cyclic perfluoroalkyl group.

Examples of the residue unit represented by the general formula (1) include the following residue units.

Of these, perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by the general formula (2) is preferable because resin particles containing the following residue units are preferable because they are excellent in heat resistance and molding processability. ) Resins containing residue units are more preferred.

Since the resin particles of the present invention have a volume average particle diameter of 5 μm or more and 2000 μm or less, they have high fluidity and can be continuously supplied to a molding machine or the like. The volume average particle diameter is preferably 5 μm or more and 1000 μm or less. Further, when the volume average particle diameter is within the above range, the solvent can be prevented from remaining on the resin particles, so that the heating weight reduction amount becomes small. The residual solvent on the resin particles can also be obtained by obtaining resin particles by a precipitation polymerization method described later.

The volume average particle diameter of the resin particles of the present invention is more preferably 5 μm or more and 500 μm or less. When the volume average particle diameter is within this range, the fluidity is higher, continuous feeding to a molding machine or the like is facilitated, and the heating weight reduction amount is also small. Furthermore, the filling property is increased as compared with the resin obtained by the method described in Non-Patent Document 1, and it becomes possible to efficiently store the resin in a container. When the volume average particle diameter is 5 μm or more, the resin particles of the present invention are less likely to be scattered by the air flow, and the handleability of the resin particles of the present invention is improved. Further, when the volume average particle diameter is 500 μm or less, the resin particles can be melted in a shorter time, and the efficiency of molding is improved, which is preferable.

The 90% particle diameter of the resin particles of the present invention is preferably 2500 μm or less, more preferably 2000 μm or less, and further preferably 1000 μm or less. Thereby, in the resin particles of the present invention, the content of coarse particles is reduced, and the fluidity and moldability are further improved.

The 10% particle diameter of the resin particles of the present invention is preferably 3 μm or more. Thereby, in the resin particles of the present invention, the content of fine particles is reduced, dusting is further prevented, and fluidity is further improved.

The volume average particle size, 90% particle size, 10% particle size and particle size distribution of the resin particles of the present invention can be evaluated by particle size distribution measurement (volume distribution) by a laser diffraction scattering method. Particle size distribution by laser diffraction scattering method is measured after dispersing resin particles in water or an organic solvent such as methanol, and subjecting the particles to a uniform state with an ultrasonic homogenizer if necessary. By doing so, it is possible to quantify with good reproducibility. As the laser scatterometer, Microtrac manufactured by Microtrac Bell Co. can be exemplified.

The volume average particle diameter is also referred to as the Mean Volume Diameter and is an average particle diameter expressed on a volume basis. The particle diameter distribution is divided for each particle diameter channel, and the representative particle diameter value of each particle diameter channel is d. It is represented by Σ(vd)/Σ(v), where v is the volume-based percentage for each particle size channel.

The 10% particle size means the particle size at the point where the cumulative amount is 10% when the cumulative amount is calculated with the total volume of the powder group as 100%. The 90% particle size represents the particle size at a point where the cumulative amount is 90% when the cumulative amount is calculated with the total volume of the powder group as 100%.

The resin particles of the present invention preferably contain no emulsifier and/or dispersant. By not containing an emulsifier and/or a dispersant, a resin and resin particles having excellent transparency and heat resistance can be obtained. The resin particles containing no emulsifier and/or dispersant can be produced by the precipitation polymerization method described below. Therefore, the resin particles of the present invention are preferably a precipitation polymer. Here, the dispersant is an agent having a function of dispersing the resin particles in a solvent, and examples thereof include polyvinyl alcohol, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose and the like. The emulsifier is an agent having a function of emulsifying resin particles in a solvent, and examples thereof include a fluorine-containing surfactant such as sodium perfluorooctanoate, sodium perfluorooctanesulfonate, and ammonium perfluorooctanoate salt; Examples include non-fluorine surfactants such as sodium lauryl sulfate and ethylene glycol-based polymers.

The bulk density of the resin particles of the present invention is preferably 0.2 g/cm ³ or more and 1.5 g/cm ³ or less from the viewpoint of filling property. The bulk density can be measured by the method described in Examples below.

The resin particles of the present invention may contain other monomer residue units, and examples of the other monomer residue units include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and chlorotriene. Fluoroethylene (CTFE), trifluoroethylene, hexafluoroisobutylene, perfluoroalkylethylene, fluorovinyl ether, vinyl fluoride (VF), vinylidene fluoride (VDF), perfluoro-2,2-dimethyl-1,3-dioxole (PDD), perfluoro(allyl vinyl ether) and perfluoro(butenyl vinyl ether).

The resin particles of the present invention preferably have an angle of repose of 5° or more and 60° or less. As a result, the fluidity of the resin particles becomes higher, and continuous supply to a molding machine or the like becomes easy. The angle of repose is more preferably 5° or more and 40° or less, further preferably 10° or more and 40° or less.

Here, the angle of repose refers to an angle formed by the ridgeline of the powder and the flat surface when the resin powder is deposited on the flat surface. The angle of repose can be evaluated by filling the container with the resin powder, allowing the resin powder to fall naturally, and measuring the angle formed by the resin powder that becomes a mountain when the resin powder is deposited on a horizontal surface. A specific method of measuring the angle of repose will be described in Examples below.

In the present invention, the molecular weight of the resin particles is not particularly limited, and examples thereof include a weight average molecular weight measured by gel permeation chromatography (GPC) of 2,500 to 2,000,000. From the viewpoint of melt viscosity and mechanical strength of the resin, it is preferably 10,000 to 1,000,000 (g/mol). At the time of measurement, polymethylmethacrylate is used as a standard sample, and the weight average molecular weight in terms of polymethylmethacrylate is calculated from the elution time of the resin particles and the standard sample.

Next, the method for producing the resin particles of the present invention will be described.

The resin particles of the present invention can be obtained, for example, by leaving a mixture of a radical polymerization initiator, a monomer represented by the following general formula (3) and an organic solvent under polymerization conditions to obtain a residue represented by the general formula (3). It can be produced by a method including a step of obtaining a resin containing a base unit.

In the formula (3), Rf ₅ , Rf ₆ , Rf ₇ and Rf ₈ have the same meanings as Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ in the formula (1), respectively.

In the formula (4), Rf ₅ , Rf ₆ , Rf ₇ and Rf ₈ have the same meanings as Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ in the formula (1), respectively.

In the method for producing resin particles of the present invention, the organic solvent has at least a monomer represented by the general formula (3) dissolved therein and a residue unit represented by the general formula (4) generated by polymerization. At least part of the contained resin is a solvent that does not dissolve and causes precipitation of the resin, and the resin generated by the above-described polymerization is precipitated as particles in the organic solvent. The organic solvent used in the method for producing resin particles of the present invention may be referred to as "precipitation polymerization solvent". More specifically, the precipitation polymerization solvent is an organic solvent that dissolves the monomer represented by the general formula (3) and does not dissolve the resin containing the residue unit represented by the general formula (4). This precipitation polymerization solvent is hereinafter referred to as precipitation polymerization solvent A. In the present invention, by using the precipitation polymerization solvent, the resin produced by the polymerization reaction can be precipitated as particles having a specific volume average particle diameter, and as a result, it is possible to produce resin particles having excellent moldability and filling properties. You can In addition, since no polymerization aid such as an emulsifier and a dispersant is used, it is possible to produce resin particles that do not contain an emulsifier and a dispersant that cause deterioration of transparency and heat resistance.

Here, the precipitation polymerization solvent A means a solvent in which the resin particles remain after the resin particles containing the residue unit represented by the general formula (4) are immersed in the organic solvent for a long time. Specifically, the resin particles having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ containing a residue unit represented by the general formula (4) are 10 times as much as the resin particles (w/w). When the resin particles can be visually confirmed to remain in the organic solvent after being immersed in the organic solvent at 50° C. for 5 hours or more, the organic solvent can be regarded as the precipitation polymerization solvent A. The precipitation polymerization solvent A is an organic solvent in which the resin sample remaining as a solid state is recovered after the solution is cooled to 25° C. after being immersed at 50° C. for 5 hours or more, and the weight reduction rate of the resin sample is less than 20% by weight. Is preferred. The weight loss rate of the resin sample is more preferably less than 12% by weight, further preferably less than 10% by weight.

The resin weight reduction rate can be measured by the following method. After the above-mentioned cooled solution is filtered with a filter, the solid on the filter is rinsed with the solvent, washed with acetone several times and then dried to recover the resin sample on the filter. The weight of the recovered resin was measured, and the value obtained by subtracting the recovered resin weight from the amount of the resin immersed in the organic solvent was divided by the amount of the resin immersed in the organic solvent. To do.

Examples of the precipitation polymerization solvent include non-halogen organic solvents such as acetone, methyl ethyl ketone, hexane and butyl acetate, chlorine organic solvents such as dichloromethane and chloroform, and organic solvents containing a fluorine atom in the molecule.

Further, as the precipitation polymerization solvent, an organic solvent containing a fluorine atom and a hydrogen atom in the molecule is preferable because a chain transfer reaction does not easily occur in radical polymerization, the polymerization yield is excellent, and a high molecular weight polymer is easily obtained. Specific precipitation polymerization solvents containing a fluorine atom and a hydrogen atom in the molecule include 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether and 2,2,2-trifluoroethyl ether. Fluoroethanol, 1,1,1,3,3,3-hexafluoroisopropanol, 1,2,2,3,3,4,4-heptafluorocyclopentane, 1H,1H-pentafluoropropanol, 1H,1H- Heptafluorobutanol, 2-perfluorobutylethanol, 4,4,4-trifluorobutanol, 1H,1H,3H-tetrafluoropropanol, 1H,1H,5H-octafluoropropanol, 1H,1H,7H-dodecafluorohepta Nol, 1H,1H,3H-hexafluorobutanol, 2,2,3,3,3-pentafluoropropyl difluoromethyl ether, 2,2,3,3,3-pentafluoropropyl-1,1,2,2 -Tetrafluoroethyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, hexafluoroisopropyl methyl ether , 1,1,3,3,3-pentafluoro-2-trifluoromethylpropyl methyl ether, 1,1,2,3,3,3-hexafluoropropyl methyl ether, 1,1,2,3,3 , 3-hexafluoropropyl ethyl ether, 2,2,3,4,4,4-hexafluorobutyl difluoromethyl ether and the like.

Among them, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro Isopropanol and 1,2,2,3,3,4,4-heptafluorocyclopentane are preferable, because they are excellent in polymerization yield and easy to obtain a high molecular weight substance, 1,2,2,3,3,4, 4-heptafluorocyclopentane is preferred. The ratio of fluorine atom to hydrogen atom in the molecule of the precipitation polymerization solvent is preferably fluorine atom:hydrogen atom=1:9 to 9:1 in terms of the number ratio of atoms, since the polymerization yield is excellent, and 1: It is more preferably 9 to 7:3, further preferably 4:6 to 7:3.

As the precipitation polymerization solvent, a fluorine atom and a hydrogen atom are contained in the molecule because the polymerization yield is excellent, and the content of hydrogen atoms in the solvent is preferably 1% by weight or more based on the weight of the solvent molecule. It is more preferably 5% by weight or more. In addition, it is preferably 1% by weight or more and 5% by weight or less, and more preferably 1.5% by weight or more and 4% by weight or less, because the polymerization yield is excellent and a high molecular weight polymer is easily obtained. Further, as the precipitation polymerization solvent, those which do not contain a chlorine atom in the molecule are preferable because they are excellent in polymerization yield and can easily obtain a high molecular weight product.

Regarding the ratio of the monomer represented by the general formula (3) and the precipitation polymerization solvent, since particles having excellent productivity and excellent flow characteristics can be obtained, the weight ratio of monomer:precipitation polymerization solvent=1: It is preferably from 99 to 50:50, more preferably from 5:95 to 40:60, even more preferably from 5:95 to 30:70.

Examples of the radical polymerization initiator when performing radical polymerization include, for example, benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-tetr-butyl peroxide, tetr-butyl cumyl peroxide, dicumyl peroxide. Oxide, tetr-butylperoxyacetate, perfluoro(di-tetr-butylperoxide), bis(2,3,4,5,6-pentafluorobenzoyl)peroxide, tetr-butylperoxybenzoate, tetr-butyl Organic peroxides such as perpivalate; 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(2-butyronitrile), 2,2′-azobisisobutyronitrile, Examples thereof include azo initiators such as dimethyl-2,2'-azobisisobutyrate and 1,1'-azobis(cyclohexane-1-carbonitrile).

In the production method of the present invention, the monomer represented by the general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by the general formula (5), The residue unit represented by the formula (4) is preferably a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by the general formula (6).

Since the resin particles of the present invention are resin particles that are less likely to foam during molding, the weight loss upon heating at 250° C. is preferably 1% by weight or less, more preferably 0.5% by weight or less. .. The minimum amount of weight loss when heated at 250° C. is not particularly limited, but may be 0.001% by weight or more, for example. Further, since the resin particles of the present invention are resin particles that are less likely to foam during molding, the residual solvent content in the resin is preferably 1% by weight or less, and 0.5% by weight or less. Is preferred. Here, the weight reduction amount at the time of heating at 250° C. refers to the weight reduction amount at 250° C. when the temperature is raised from 40° C. at 10° C./min in an air stream using TG-DTA, and (1- (Sample weight at 250° C.)/(weighed sample weight))×100).

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Volume average particle size>
The volume average particle diameter (unit: μm) was measured using MT3000 manufactured by Microtrac Co., Ltd., using methanol as a dispersion medium.

<10% particle size>
A 10% particle size (unit: μm) was measured using MT3000 manufactured by Microtrac and using methanol as a dispersion medium.

<90% particle size>
90% particle size (unit: μm) was measured using MT3000 manufactured by Microtrac Co., Ltd., using methanol as a dispersion medium.

<Liquidity>
When the shape of the resin was particulate, it was evaluated as good (◯), and when it was not particulate, it was evaluated as bad (x).

<bulk density>
The resin particles were dropped and filled up to the mark line of 50 mL in the graduated cylinder without impacting the graduated cylinder. The weight (g) of the resin particles per 50 mL of this volume was measured. The bulk density (g/mL) was calculated by dividing the weight of the resin particles by the volume.

<Fillability>
A bulk density of 0.2 g/mL or more was rated as good (◯), and a bulk density of less than 0.2 g/mL was rated as poor (x).

<Weight average molecular weight Mw>
The measurement was performed using a column TSKgel SuperHZM-M manufactured by Tosoh Corporation and gel permeation chromatography equipped with an RI detector. Asahi Klin AK-225 (manufactured by Asahi Glass Co., Ltd.) as an eluent, and 10 wt% of 1,1,1,3,3,3-hexafluoro-2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) with respect to AK-225. Was used. A standard polymethylmethacrylate manufactured by Agilent was used as a standard sample, and the weight average molecular weight Mw in terms of polymethylmethacrylate was calculated from the elution time of the sample and the standard sample.

<250°C heating weight loss>
About 10 to 15 mg of the sample is weighed in an aluminum sample pan (SSC000E030 manufactured by Hitachi High-Tech Science Co., Ltd.) and is measured by a TG/DTA device (TG/DTA6200AST2 manufactured by Hitachi High-Tech Science Co., Ltd.) under an instrument air flow (160 mL). /Min), the temperature is increased from 40°C to 300°C at 10°C/min, and the weight loss amount at 250°C (1-(sample weight at 250°C)/(weighed sample weight)) x 100) is calculated to obtain 250 The weight loss by heating at ℃ was used.

<Angle of repose>
A sample bottle was filled with 7 ml of resin powder, and on a circular base (made of glass) having a diameter of 4 cm, a glass powder funnel (manufactured by AS ONE Co., Ltd., the diameter of the upper part of the funnel was 50 mm, the diameter of the lower part of the funnel was 10 mm, and the total length of the funnel was 100 mm, The height of the funnel foot (40 mm) is fixed so that the lower end of the powder funnel is 4 cm above the circular base, and the funnel is used to drop the resin powder from the height of the upper end of the funnel. The angle (°) of the slope was measured by a protractor (in the comparative example, the resin powder was not flowable, so the resin powder was dropped without using a powder funnel).

(Example 1) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor-type stirring blade, a nitrogen introduction tube and a thermometer was replaced with nitrogen. did. 1.288 g (0.00305 mol) of bis(2,3,4,5,6-pentafluorobenzoyl)peroxide as an initiator and perfluoro(4-methyl-2-methylene-1,3-) as a monomer Dioxolane) 150.0 g (0.615 mol), Asahi Klin AE-3000 (manufactured by Asahi Glass, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, solvent molecule as a precipitation polymerization solvent) The content of hydrogen atoms in the solvent was 1.51% by weight, and 1340 g of fluorine atoms:hydrogen atoms in the solvent molecule=7:3 (number ratio) was added, and precipitation polymerization was carried out by maintaining the mixture at 55° C. for 24 hours while stirring. went. After cooling to room temperature, the liquid containing the purified resin particles is filtered off, washed with acetone, and vacuum dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (Resin A). Was obtained (yield: 56%). Table 1 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. The resin particles obtained were excellent in fluidity and filling property. The weight average molecular weight Mw of Resin A thus obtained was 4.4×10 ⁵ .

(Comparative Example 1) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin Bis(2,3,4,5,6-pentafluorobenzoyl) was used as an initiator in a glass ampoule having a volume of 75 mL. 0.017 g (0.0000407 mol) of peroxide, 5.0 g (0.0205 mol) of perfluoro(4-methyl-2-methylene-1,3-dioxolane) as a monomer, hexafluorobenzene( Content of hydrogen atom in solvent molecule: 0% by weight, fluorine atom in solvent molecule: hydrogen atom = 10:0 (number ratio)) 8.2 g was added, and nitrogen substitution and depressurization were repeated, and then under reduced pressure. It was sealed. This ampoule was placed in a constant temperature bath at 55° C. and held for 24 hours for radical solution polymerization, whereby a viscous liquid in which a resin was dissolved was obtained. After cooling to room temperature, the ampoule was opened and the resin solution was diluted with 36 g of hexafluorobenzene to adjust the viscosity to prepare a resin diluted solution. 1 L of chloroform was added to a beaker equipped with an anchor blade, and the resin was diluted by adding the resin diluted solution to the chloroform under stirring to precipitate the resin, followed by vacuum drying to obtain perfluoro(4-methyl-2-methylene). -1,3-Dioxolane) resin (Resin D) was obtained (yield: 61%). The weight average molecular weight Mw of the obtained resin D was 3.5×10 ⁵ . Table 1 shows the shape, bulk density, and angle of repose of the obtained resin. The volume average particle diameter could not be measured because the resin was amorphous. In some cases, the obtained resin had problems in fluidity and filling property.

(Example 2) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles A 1 L SUS316 autoclave equipped with an anchor type stirring blade, a nitrogen introducing tube and a thermometer was replaced with nitrogen. did. 0.346 g (0.000820 mol) of bis(2,3,4,5,6-pentafluorobenzoyl)peroxide as an initiator and perfluoro(4-methyl-2-methylene-1,3-) as a monomer. Dioxolane) 100.0 g (0.410 mol), 2,2,2-trifluoroethanol as a precipitation polymerization solvent (hydrogen atom content in solvent molecule: 3.03% by weight, fluorine atom in solvent molecule: hydrogen) 890 g of atoms=5:5 (number ratio) were added, and precipitation polymerization was carried out by stirring and holding at 55° C. for 24 hours.Cooling to room temperature, filtering the liquid containing purified resin particles and washing with acetone Then, vacuum drying was performed to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin B) (yield: 78%). The average particle size, 10% particle size, 90% particle size, bulk density, and angle of repose are shown in Table 1. The resin particles obtained were excellent in fluidity and filling property. The average molecular weight Mw was 1.1×10 ⁵ .

(Example 3) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor type stirring blade, a nitrogen introducing tube and a thermometer was replaced with nitrogen. did. 0.519 g (0.00123 mol) of bis(2,3,4,5,6-pentafluorobenzoyl)peroxide as an initiator and perfluoro(4-methyl-2-methylene-1,3-) as a monomer. Dioxolane) (150.0 g, 0.615 mol) and chloroform (1150 g) as a precipitation polymerization solvent were added, and the mixture was maintained at 55° C. for 24 hours with stirring to carry out precipitation polymerization. After cooling to room temperature, the liquid containing the purified resin particles is filtered off, washed with acetone, and vacuum dried to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (Resin C). Was obtained (yield: 19%). Table 1 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. The resin particles obtained were excellent in fluidity and filling property. The weight average molecular weight Mw of the obtained resin C was 7.0×10 ³ .

(Example 4) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles A 1 L SUS316 autoclave equipped with an anchor type stirring blade, a nitrogen introducing tube and a thermometer was replaced with nitrogen. did. 1.038 g (0.00246 mol) of bis(2,3,4,5,6-pentafluorobenzoyl)peroxide as an initiator and perfluoro(4-methyl-2-methylene-1,3-) as a monomer. Dioxolane) 300.0 g (1.23 mol), Zeorora-H (manufactured by Zeon Corporation, 1,2,2,3,3,4,4-heptafluorocyclopentane as a precipitation polymerization solvent, hydrogen atom in the solvent molecule) Content: 1.55% by weight, 1200 g of fluorine atom:hydrogen atom in solvent molecule=7:3 (number ratio) was added, and precipitation polymerization was carried out by maintaining the mixture at 55° C. for 24 hours with stirring. After cooling to room temperature, the liquid containing the purified resin particles was filtered off, washed with acetone, and dried in vacuum to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (Resin E). Was obtained (yield: 86%). Table 2 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. The resin particles obtained were excellent in fluidity and filling property. The weight average molecular weight Mw of the obtained resin E was 4.9×10 ⁵ .

(Example 5) Production of perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles The inside of a 1 L SUS316 autoclave equipped with an anchor type stirring blade, a nitrogen introducing tube and a thermometer was replaced with nitrogen. did. 0.519 g (0.00123 mol) of bis(2,3,4,5,6-pentafluorobenzoyl)peroxide as an initiator and perfluoro(4-methyl-2-methylene-1,3-) as a monomer. Dioxolane) 150.0 g (0.615 mol), 1,1,1,3,3,3-hexafluoroisopropanol as a precipitation polymerization solvent (content of hydrogen atoms in solvent molecule: 1.82% by weight, solvent molecule) 1340 g of fluorine atom:hydrogen atom=6:4 (number ratio) therein was added, and precipitation polymerization was carried out by maintaining the mixture at 55° C. for 24 hours with stirring. After cooling to room temperature, the liquid containing the purified resin particles was filtered off, washed with acetone, and dried in vacuum to obtain perfluoro(4-methyl-2-methylene-1,3-dioxolane) resin particles (resin F). Was obtained (yield: 59%). Table 2 shows the shape, volume average particle diameter, 10% particle diameter, 90% particle diameter, bulk density, and angle of repose of the obtained resin particles. The resin particles obtained were excellent in fluidity and filling property. The weight average molecular weight Mw of the obtained resin F was 7.9×10 ⁵ .

(Reference example 1)
The resin particles obtained in Example 1 were immersed in 10 times the amount of various solvents at 50° C. for 5 hours, and it was visually observed whether the resin particles remained.

-The organic solvents in which residual resin particles were visually confirmed are as follows:
1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoroisopropanol, 1 , 2,2,3,3,4,4-heptafluorocyclopentane, chloroform.

Then, after cooling to 25° C. and filtering with a filter, the resin particles were taken out by rinsing and washing with the solvent, and then the resin particles were washed twice with 10 times the amount of acetone, vacuum dried, and the recovery rate from the dry weight. Was found to be 90% or more. When the filtrate obtained above was distilled off and the solid content in the filtrate was determined, the solid content in the filtrate was less than 10% based on the resin particles used. From the above results, it was confirmed that the weight reduction rate of the resin weight was less than 10% by weight.

(Reference example 2)
The resin particles obtained in Example 1 were immersed in a 10-fold amount of the various solvents described below at 50° C. for 5 hours, and it was visually observed whether the resin particles remained.

The organic solvents in which the resin particles were not visually observed to remain are as follows:
Hexafluorobenzene, CF ₃ CF ₂ CHCl ₂ (hydrogen atom content in solvent molecule: 0.55% by weight, fluorine atom: hydrogen atom in solvent molecule=8:2 (number ratio))
As a result of visual observation at 50° C., all the solutions were transparent, and turbidity was hardly confirmed. Then, the mixture was cooled to 25° C., filtered with a filter, rinsed with the solvent, the filter was vacuum dried, and the recovery rate was calculated from the weight increase of the filter. As a result, all were less than 5% by weight. From the above results, it was confirmed that the weight loss rate of the resin after immersion in the solvent was 95% by weight or more.

The present invention provides fluororesin particles which are excellent in fluidity and filling property and have a small heating weight reduction amount, and a method for producing fluororesin particles.

Claims (15)

A resin particle comprising a residue unit represented by the following general formula (1) and having a volume average particle diameter of 5 μm or more and 2000 μm or less.
(In the formula (1), Rf ₁ , Rf ₂ , Rf ₃ and Rf ₄ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched perfluoroalkyl group having 3 to 7 carbon atoms. 1 represents one of a group consisting of a perfluoroalkyl group or a cyclic perfluoroalkyl group having a carbon number of 3 to 7. The perfluoroalkyl group may have an etheric oxygen atom, and Rf ₁ and Rf. ₂ , Rf ₃ and Rf ₄ may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may be a ring containing an etheric oxygen atom.) The resin particles according to claim 1, wherein the volume average particle diameter is 5 μm or more and 500 μm or less. The resin particle according to claim 1 or 2, which has an angle of repose of 5° or more and 60° or less. The resin particle according to any one of claims 1 to 3, wherein the resin particle is a precipitation polymer. The resin particle according to any one of claims 1 to 4, which has a bulk density of 0.2 g/mL or more and 1.5 g/mL or less. The resin particles according to any one of claims 1 to 5, wherein the weight loss upon heating at 250°C is 1% by weight or less. The resin particles according to claim 1, wherein the resin particles do not contain an emulsifier and/or a dispersant. The residue unit represented by the general formula (1) is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residue unit represented by the general formula (2). The particle according to any one of claims.
A step of subjecting a mixture of a radical polymerization initiator, a monomer represented by the following general formula (3) and an organic solvent to polymerization conditions to obtain a resin containing a residue unit represented by the general formula (4). Have,
The organic solvent, at least the monomer is dissolved, and at least a part of the resin produced by the polymerization is not dissolved, is a solvent that causes precipitation of the resin,
The method for producing resin particles according to claim 1, wherein the resin produced by the polymerization is precipitated as particles in an organic solvent.
(In the formula (3), Rf ₅ , Rf ₆ , Rf ₆ , and Rf ₇ are each independently a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, or a branched chain having 3 to 7 carbon atoms. Represents a perfluoroalkyl group or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms, wherein the perfluoroalkyl group may have an etheric oxygen atom, and Rf ₅ , (Rf ₆ , Rf ₆ and Rf ₇ may be linked to each other to form a ring having 4 to 8 carbon atoms, and the ring may be a ring containing an etheric oxygen atom.)
(Definition of _{Rf 5, Rf 6, Rf 6} , and Rf ₇ in the formula (4) are the same as defined formula _{(3) Rf 5, Rf 6} , Rf 6, and Rf ₇ definitions in.) The said organic solvent is an organic solvent which melt|dissolves the monomer represented by General formula (3), but does not dissolve the resin containing the residue unit represented by General formula (4). Manufacturing method. The organic solvent contains resin particles having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ including a residue unit represented by the general formula (4), which is 10 times (w/w) the resin particles. 11. The production method according to claim 10, wherein the organic solvent is capable of visually confirming that the resin particles remain in the organic solvent after being immersed in the organic solvent at 50° C. for 5 hours or more. The organic solvent contains resin particles having a weight average molecular weight Mw of 5×10 ⁴ to 70×10 ⁴ including a residue unit represented by the general formula (4), which is 10 times (w/w) the resin particles. After immersing in the organic solvent of 50) at 50° C. for 5 hours or more, the solution is cooled to 25° C., and the resin sample remaining as a solid state is recovered, and the weight loss rate of the resin sample is less than 20% by weight. The manufacturing method according to claim 10 or 11. 13. The production method according to claim 9, wherein an organic solvent containing a fluorine atom and a hydrogen atom is used in the molecule. The method according to claim 13, wherein an organic solvent having a hydrogen atom content in the solvent molecule of 1% by weight or more is used. The monomer represented by the general formula (3) is perfluoro(4-methyl-2-methylene-1,3-dioxolane) represented by the general formula (5), and is represented by the general formula (4). 14. The production according to any one of claims 9 to 13, wherein the residual unit is a perfluoro(4-methyl-2-methylene-1,3-dioxolane) residual unit represented by the general formula (6). Method.